Device for removing bulk material from storage

ABSTRACT

A device for removing bulk material from storage in a dump pile includes at least one scraper arranged to be raised and lowered on a gantry spanning the dump.

United States Patent [191 Striicker [54] DEVICE FOR REMOVING BULK MATERIAL FROM STORAGE [75] Inventor: Giinter Striicker, Holzwickede, Germany [73] Assignee: Gustav .Schade Maechineniabrlk,

Dortmund, Germany [22] Filed: Feb. 2, 1971 [21] Appl.No.: 111,845

[30] Foreign Application Priority Data Feb. 5, 1970 Germany ..P 20 05 147.2

[52] US. Cl ..198/36, 214/10 [51] Int. Cl ..B65g 65/28 [58] Field of Search ..214/10; 198/9, 36, 77, 79

[56] References Cited UNITED STATES PATENTS 3,557,934 2/1969 Schade ...198/36 [111 3,708,056 11 Jan. 2, 1973 1,570,360 1/1926 Lippoldt 198/79 1,574,143 2/1926 White ..198/77 X 3 ,509,985 5/1970 Fischer 198/36 FOREIGN PATENTS OR APPLICATIONS 1,127,806 4/1962 Germany ..214/10 603,086 9/1934 Germany ..214/10 Primary Examiner-Drayton E. Hloffman Assistant Examiner-Frank E. Werner Attorney-Meyer, Tilberry & Body [5 7] ABSTRACT A device for removing bulk material from storage in a dump pile includes at least one scraper arranged to be raised and lowered on a gantry spanning the dump.

17 Claims, 6 Drawing Figures PATENTEUJAI 2191a SHEET 2 BF 3 IN VEN TOR Pmmmm 21915 3.708 056 SHEET 3 OF 3 DEVICE FOR REMOVING BULK MATERIAL FROM STORAGE BACKGROUND OF THE INVENTION This application pertains to the art of materials handling and more particularly to handling of bulk materials. The invention is particularly applicable to scraping of bulk material from a storage dump pile and will be described with particular reference thereto, although it will be appreciated that the invention has broader applications and may be used for other purposes.

Known service scrapers, including some of gantry design, are equipped with an articulated job. An articulated jib of this type includes two jib elements which are articulated to each other, and are pivotal relative to each other in the vertical plane. Each jib element has a separate scraper chain drive. Apart from the fact that such devices for the removal of material from storage are relatively costly to construct, they also have the disadvantage that, in the case of bulk material which has hardened, transfer difficulties are frequently encountered at the articulation point of the jib. Finally, in these devices, the maximum dump width which can be covered with the articulated jib is limited because the transverse stability of the articulated jib is considerably impaired due to the articulation.

Also known are removal devices of gantry design which, instead of an articulated jib, include two separate scraper jibs, one of which is articulated for raising and lowering to one of the bases of the gantry, and the other of which is similarly connected to the opposite gantry base. In this case, the arrangement may be such that one of the jibs conveys the material up the slope of the dump, which in cross-section is triangular, into the conveying zone of the further scraper jib which scrapes it downwardly on the opposite slope and feeds it to a stationary storage yard belt to be conveyed away. In the case of devices of this type, particularly with bulk material which has hardened and exhibits a tendency to stick, difficulty may result during the transfer of the material from the scraper jib connected upstream and the scraper jib connected downstream. Furthermore, it is disadvantageous that the scraper jib connected upstream is required to convey the material up the slope. In the case of dumps having considerable base widths, this involves large jib lengths. The scraper jibs then project, in the raised position, to a greater or lesser extent upwardly above the dump or the gantry. Additionally, in order to afford the necessary transverse stability, the jibs must be constructed in relatively strong and heavy form.

The invention is based predominantly on the problem of how to provide an apparatus for the removal of material from storage which is of relatively simple, space-saving and operationally reliable design, and arranged so that extremely wide dumps may be cleared economically, while at the same time dispensing with a scraper jib extending upwardly to a considerable extent.

SUMMARY OF THE INVENTION The apparatus for removal of bulk material from storage according to the invention is characterized in that the scraper for removal from storage extends over the entire dump width, and is adapted to be lowered substantially into the horizontal position and substantially parallel to itself.

The apparatus for removal from storage according to the invention thus has, at the gantry, a substantially horizontally suspended scraper which, in this position, is adapted to be lowered as far as the base of the dump and to convey the bulk material on the upper side of the dump pile. The dump pile is trapezoidal in crosssection to one of the dump slopes, so that material is able to slide down on the slop into or onto a sequentially connected conveyor, such as a stationary storage yard belt or the like.

The scraper for removal from storage may, according to a further important feature of the invention, be supported at both its ends in or on the gantry frame. Due to the support on both sides of the scraper, the bending loading thereof is greatly diminished, so that the scraper can be dimensioned to be extremely long for clearing wide dumps, while at the same time keeping the manufacturing expense: within reasonable limits.

It is advisable to guide the scraper at both of its ends in a vertical guideway of the displaceable gantry. The said vertical guideways are preferably designed so that the scraper is supported in the guideways against lateral forces, that is, against horizontal thrust forces. Particularly advantageous is a design wherein one end support for the scraper is designed as a fiixed bearing and the other end as a loose bearing. With such an arrangement, relative movements in the longitudinal direction of the scraper may occur between the latter end and the gantry in the vertical guideway.

According to a further aspect of the invention, the scraper carries at each of its ends a slide, carriage or trolley which is supported on the gantry and guided in the vertical direction. The two slides, carriages or trolleys may also have directly associated with them the drive for raising and lowering the scraper. On the other hand, according to the invention, it is also possible to suspend the scraper between its ends from at least two points so that during removal of material from storage the scraper may be lowered into a horizontal position parallel to itself.

In an apparatus of the type described, the scraper extends over the entire dump width and is of elongate construction. The device is also substantially horizontally arranged so that a pivoting boom of known design which projects far beyond the gantry is avoided. Thus, the entire device has a structuralheight which is only slightly greater than the dump height. The device according to the present invention adapts itself very closely, in space-saving manner, to the contours of the dump pile.

It will be recognized that it would also be possible to adjust the scraper during removal of material from storage in a substantially oblique direction with respect to the horizontal. This adjustment being readily achieved by appropriate actuation of the lifting device which may comprise two individual lifting winches or a double-drum winch. This oblique positioning of the upstream-connected scraper may be necessary in particular when the dump base is designed, in a known manner, as an obliquely ascending :ramp.

According to a further feature of the invention, a clearing device is arranged on the gantry for working on that dump slope down which bulk material slides after clearing from the horizontal scraper. The clearing device has in general only the task of maintaining the dump slope at the natural angle of repose for the bulk material. Thus, the clearing device assists the downward movement of bulk material fed from the horizontal scraper. For the clearing device, it is possible to use devices of various construction, such as clearing beams, bulldozers, worm conveyors and the like. Particularly expedient is the use of a scraper working as a subsidiary scraper solely on the dump slope. The subsidiary scraper has a length, in the case of a wide bulk material dump, which is substantially smaller than the length of the horizontally arranged main scraper. Since the subsidiary scraper generally has the task only of keeping the dump slope free and supporting the downward movement of the bulk material fed from the horizontal scraper, the subsidiary scraper may be arranged on the gantry in non-variable angular position corresponding substantially to the natural angle of repose of the bulk material. Naturally, the same holds true when clearing devices of a different type are used instead of the subsidiary scraper.

On the other hand, according to the invention, it is also possible to so arrange the subsidiary scraper on the gantry that the angular position thereof may be varied. In this case, it is advisable to mount the subsidiary scraper at one of its ends, expediently at the lower end, in an articulation means having a horizontal articulation axis. It is also desirable to associate the subsidiary scraper with a separate lifting device so that the subsidiary scraper may be pivoted in a vertical plane about the articulation axis. With an arrangement of this kind, it becomes possible to use the subsidiary scraper together with the horizontal scraper or independently thereof for clearing the bulk material dump in the manner of a known scraper jib.

According to a further feature of the invention, the clearing device or the subsidiary scraper is arranged as seen in plan view, offset relative to the main scraper proper in a direction opposite to the direction of travel of the main scraper. Thus, the clearing device or the subsidiary scraper conveys the heap material, during the productive or extraction travel of the apparatus for removal from storage, downwardly on the dump slope. The said heaped material cleared by the subsidiary scraper is material which had previously been fed by the advancing main scraper to the dump slope. In order that the apparatus for removal from storage according to the invention may be able to operate in both directions of travel, it is desirable to provide two clearing devices or subsidiary scrapers on the gantry frame. Such subsidiary scrapers are adapted to travel along both sides of the heap or dump pile. One such clearing device or subsidiary scraper is arranged before the main scraper in its direction of travel and the other thereof is arranged behind the main scraper in its direction of travel. On using scrapers as clearing apparatus, the two subsidiary scrapers set up at the angle of the dump slope are generally adjusted to the same incision depth. With such an arrangement, substantially only the subsidiary scraper trailing in the direction of travel of the main scraper performs a removal function. On the other hand, it is also possible to adjust the two subsidiary scrapers to be offset relative to each other through an incision depth in each particular case so that both subsidiary scrapers perform removal from storage work in each direction of travel of the apparatus.

The principle feature underlying the invention is an arrangement whereby a substantially horizontally arranged scraper jib is adapted to be lowered without noteworthy pivoting and longitudinal movement as far as approximately the base of the dump. The scraper jib is preferably supported and guided at both ends in a manner affording a large number of variable embodiments of the apparatus for removal of material from storage. For example, it is also possible, instead of having only a single main scraper on the gantry, to arrange two scrapers for removal of material. Two such scrapers are positioned in parallel arrangement for lowering substantially horizontally and parallel to themselves. Two such scrapers may also be offset relative to each other by the amount of the incision depth during the work required for removal of material from storage so that both scrapers perform removal from storage work. With this design of the scraper for removal of material according to the invention, it is preferable to so arrange the clearing device or subsidiary scraper which operates on the dump slope on the gantry between the two horizontal scrapers as seen in plan view.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof.

FIG. 1 shows a device for removal of material from storage according to the invention, diagrammatically and as a lateral elevation;

FIG. 2 shows the device for removal of material according to FIG. 1 with subsidiary scrapers operating on the dump slope;

FIG. 3 shows a plan view of the arrangement according to FIG. 2, the upper portion of the gantry frame being omitted for clarity of illustration;

FIG. 4 shows a plan view of the horizontal scraper for removal of material from storage, and illustrating an expedient design of the vertical guideway of the said scraper;

FIG. 5 shows another form of the invention wherein the device for the removal from storage includes two horizontal scrapers; and

FIG. 6 is a diagrammatic illustration of a cross-section through the two scrapers according to FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein the showings are only for purposes of illustrating a preferred embodiment of the invention and not for purposes of limiting same, FIG. 1 shows a bulk material dump 10 which is trapezoidal in cross-section. The base of the dump or the base of the storage place is constituted by a ramp surface 11 ascending gradually to a lateral dump-limiting wall 12. Extending laterally adjacent the said limiting wall 12 and along the dump 10 is a stationary storage yard belt 13 via which the bulk material to be extracted from the dump is removed.

Reference numeral 14 designates parallel rails extending laterally adjacent the opposite sides of the dump base and on which a gantry l5 spanning the dump travels by means of driven travel wheels 16. The

gantry 15 is thus adapted to be displaced along the dump in both directions.

Gantry includes two vertical base portions 17 and 18 connected via a horizontal gantry bridge 19 to form a frame which, as seen in lateral elevation, is substantially U-shaped and closely surrounds dump 10.

Gantry base portion 17 is designed as an oscillating strut and is pivotally connected with gantry bridge 19 via an articulation means 20 having a horizontal articulation axis. The opposite gantry base portion or gantry leg 18 is connected with gantry bridge 19 to be angularly rigid.

Suspended in substantially horizontal position from gantry 15 is a scraper 21 for removal of material from storage, the length of the said scraper being substantially equal to the base width of the dump. Scraper 21 includes a girder of known construction, such as a box girder of welded construction, at both ends of which are mounted sprocket wheels 22 and 23 over which two endless parallel chains 24 are driven. The two chains 24 are connected with each other by scraper elements (not shown) which engage the bulk material at the dump surface and convey it in the direction of arrow P toward dump slope 10'.

Scraper 21 is so suspended between its ends to gantry bridge 19, through the agency of two lifting devices 25, that it may be lowered from the raised position shown as far as the base of the dump. The two lifting devices 25, which expediently include two separate lifting winches or of a joint winch equipped with a double drum, may be so actuated that the scraper 21 may be lowered substantially into the horizontal position approximately parallel to itself, by the necessary cutting feed in each particular case. When so doing, the lowering procedure may be so effected that the scraper will, at least in the lower position shown in dot-dash lines in the drawings and designated 21 be adjusted in adaptation to the ramp-like oblique face 11 somewhat obliquely relative to the horizontal.

Scraper 21 for removal of material from storage is laterally supported at both ends in gantry 15. The oscillating strut 17 has, as best shown in FIG. 3, a vertical slot guideway 26 receiving a fork-like guide projection 27 secured at one end to scraper 21 for guiding in the vertical direction. Under the influence of the horizontal thrust forces arising during the work of removal from storage, scraper 21 bears, via the guide projection 27, laterally on one of the two opposite faces 26' of vertical guideway 26.

At the opposite end, scraper 21 is again guided and supported in a vertical guideway. The said vertical guideway includes a vertical guide slot 31 formed in gantry leg 18. Opposed U-shaped guide rails 28 are secured to the opposite sides of slot 31. Travel rollers 29 mounted laterally on the cheeks of a fork-like guide projection 30 on the scraper 21 are guided in U-shaped guide rails 28.

It will be appreciated that the bearing arranged on gantry leg 18 of scraper 21 is designed in the form of a fixed bearing in which the scraper for removal of material from storage is displaceable in the vertical direction and mounted for pivoting about a horizontal articulation axis, but is not displaceable in its longitudinal direction. On the other hand, the opposite hearing on gantry leg 17 is designed as a loose bearing so that relative movements in the longitudinal direction of the scraper between the latter and gantry leg 17 are possible. This bearing is thus designed as an oscillating support. 1

During the work for removal of material from storage, gantry 15 of FIG. 1 travels along dump 10. If dump 10 is built up as an annular dump, then gantry 15 travels on an arc of a circle path along the dump. Horizontal scraper 21 for removal of material from storage 21 has been lowered to such an extent by means of the lifting devices 25 that it bears on the upper side of the dump and conveys the bulk material by means of its scraper in the direction of arrow P towards the slope 10'. The bulk material then slides over slope 10' downward on to the storage yard belt 13 from which it is conveyed-away out of the zone of the dump. When the device for removal from storage has reached the end of the dump, horizontal scraper 21 for removal of material from storage is lowered by the incision or cutting depth of its scrapers, whereupon the device for removal from storage travels in the opposite travel direction along the dump and clears the latter by the amount of a further cutting depth. This procedure is repeated until the dump has been cleared over the entire cross-section. Scraper 21 is then in position 21 indicated by dot-dash lines in FIG. 1, wherein it bears flat on ramp face 11. Since ramp face 11 is inclined relative to the horizontal, scraper 21 must, at least when it has cleared the dump as far as substantially the upper edge of ramp 11, be pivoted slightly out of its horizontal working position into the oblique position 21' shown in dot-dash lines. This may readily be effected by lowering the scraper adjacent gantry leg 17 somewhat further than adjacent the gantry leg 18 by means of lifting and lowering devices 25.

The device for removal from storage according to FIGS. 2 and 3 differs from that according to FIG. 1 only in that it is provided with a clearing device operating on dump slope 10. The task of this clearing device is predominantly to maintain the dump slope during the removal from storage procedure and to aid the downward conveying of bulk material fed from the horizontal scraper to dump slope 10'.

As may be gathered from FIGS. 2 and 3, there are mounted laterally adjacent vertical guideway 31 on gantry leg 18, two subsidiary scrapers 32 and 32' designed as scraper jibs. Scrapers 32 and 32' are positioned in pivot bearings 33 having horizontal articulation axes. Subsidiary scrapers 32 and 32' have a length which is smaller by a multiple than the length of main scraper 21. The two subsidiary scrapers 32 and 32' are, according to FIG. 2, arranged at an angle corresponding to the natural angle of repose of the bulk material on dump 10. At their upper ends, scrapers 32 and 32' are connected via arms 34 or other coupling means with the gantry bridge 19. Subsidiary scrapers 32 and 32' are also supported at both ends on the gantry, the arrangement being expediently such that the angular position of the subsidiary scrapers is adjustable within a predetermined adjustment range.

It will be appreciated that subsidiary scrapers 32 and 32' engage, during the removal from storage work, the bulk material fed from scraper 21 and convey it downwardly on slope 10' so that it passes on to storage yard belt 13. With this arrangement, only those subsidiary scrapers located behind the scraper 21 in its direction of travel are usually operative. Subsidiary scrapers 32 and 32' retain their oblique position according to FIG. 2 during the work of removal from storage. Lowering of the said scrapers after each productive travel is therefore not necessary per se. Of course, it would be possible to so employ the two scraper jibs 32 and 32' so that they not only clear the bulk material fed from or by main scraper 21 but also cut into and remove material from slope FIG. 4 shows an expedient design of the bearings and vertical guideways of horizontal scraper 21 for removal of material from storage. The scraper for removal from storage carries, at its end facing gantry leg 18, a guide frame 40 which is designed in the manner of a slide or carriage and which has at its two opposite lateral faces travel rollers 41 with the aid of which it is guided on U- shaped guide rails 42. The two guide rails 42 are secured to the lateral faces of vertical guideway 31 on gantry leg 18. Guide frame 40 is so secured with its two limbs 40' laterally to box girder 43 of scraper 21 that limbs 40' laterally engage about reversing roller 44 for reversing or deflecting the two endless scraper chains 45 and enclose the same between them. Guide frame 40 is formed with a recess 46 adapted to the shape of scraper elements 47 secured between the two endless chains 45 so that the scraper elements are, during their travel about reversing roller 45, able to travel through the said recess 46. It will be appreciated that frame 40 is mounted to be vertically displaceable by means of its travel rollers 41 and simultaneously pivotal about a horizontal pivot in the roller guideways.

On the opposite side, scraper 21 also has a guide frame 48 which in plan view is substantially U-shaped and which is so secured, through the agency of its two limbs 48', to the lateral cheeks of box girder 43 that scraper elements 47 travel, on travelling about chain drums 49, through interior space 50 of the guide frame. Guide frame 50 has, at its two opposite vertical faces, wearing pieces 51 with the aid of which it is able to bear against slide faces 52 arranged laterally in vertical guideway 26 of gantry leg 17.

It will be perceived that guide frame 28 is displaceable, in vertical guideway 26, not only in the vertical direction, while being pivotal in the vertical plane, but is also able to travel, relatively to gantry leg 17, in the longitudinal direction of scraper 21. In this way, it is ensured that no compulsive forces can be set up between gantry leg 17 and guide frame 48 or the scraper 21.

FIGS. 5 and 6 show a further advantageous example of another embodiment of the device for removal of material from storage according to the invention. The said device also corresponds to a considerable extent to that according to FIG. 1. However, in this case, there are provided parallel to each other two substantially horizontal scrapers 21, both of which are supported and guided in vertical guideways of gantry legs 17 and 18. The supporting and guiding corresponds to that according to FIG. 3, although the arrangement according to FIG. 4 could also be used. Between scrapers 21, and arranged in spaced relationship, is a clearing device taking the form of a subsidiary scraper 32. In respect of its design, functioning, mounting and supporting on the gantry, scraper 32 corresponds to the subsidiary scraper according to FIGS. 2 and 3.

Scrapers 21 are designed to be lowered independently of each other while retaining their parallel position so that they may be adjusted relative to each other by the amount of the incision or cutting depth. This is shown in FIG. 6. It will be perceived that scraper 21 arranged rearwardly in the direction of travel S of the gantry (on the right-hand side in FIG. 6), lowered further by the amount of the cutting feed so that on movement of the gantry in the direction of arrow S both scrapers 21 perform removal from storage work. Subsidiary scraper 32 disposed between the two substantially horizontally arranged scrapers 21 performs, in this case, merely a clearing function. Thus, it serves for clearing the bulk material fed from the particular advancing scraper 21 to dump slope 10', from the slope or supporting the same during its downward movement on the slope. The bulk material fed by the trailing scraper 21 to slope 10' is cleared from the slope by subsidiary scraper 32, during the following removalfrom storage travel, in the direction opposite to that of arrow S, to the extent that it has not already slid under the influence of gravity over the slope on to the storage yard belt 13.

It is self-evident that, also in the case of the embodiment according to FIGS. 5 and 6, it will be possible to dispense with a clearing device or a subsidiary scraper if what is concerned is a relatively loose and flowable bulk material which will slide down the dump slope of its own accord. However, the use of a clearing device is always to be recommended if the bulk material has a tendency to sticking and caking.

While the invention has been described with regard to certain preferred arrangements, it is obvious that alterations and modifications will be apparent to those skilled in the art upon reading this specification. The present invention includes all such obvious and equivalent alterations and modifications and is limited only by the scope of the claims.

Having thus described my invention, I claim:

1. A device for removing material from a storage dump pile having a predetermined width and a sloping face, said device including a movable gantry spanning said dump pile and being movable along said pile in a direction of movement, scraper means movably supported by said gantry for raising and lowering movement in a substantially horizontal position for removing material from said pile, and clearing means supported by said gantry in a position offset from said scraper means parallel to said direction of movement of said gantry for clearing material from said sloping face of said pile.

2. The device of claim 1 wherein said clearing means comprises two subsidiary scrapers supported by said gantry on opposite sides of said scraper.

3. The device of claim 2 and further including adjustment means for adjusting the position of said subsidiary scrapers.

4. The device of claim 1 wherein said scraper means comprises a pair of scrapers positioned in parallel spaced-apart relationship and said clearing means is positioned between said pair of scrapers.

5. The device of claim 4 wherein said clearing means comprises a subsidiary scraper.

6. The device of claim 1 wherein said scraper means has opposite end portions, suspension means movably suspending said scraper means from said gantry for raising and lowering movement in a substantially horizontal position, said suspension means being connected to said scraper means in at least two spacedapart points intermediate said end portions.

7. The device of claim 6 wherein said gantry has spaced-apart upright legs, and lateral support means for laterally supporting said opposite end portions of said scraper means on said legs.

8. The device of claim 1 wherein said clearing means comprises a subsidiary scraper having opposite end portions, and articulation means supporting at least one of said end portions on said gantry for raising and lowering movement of said subsidiary scraper.

9. The device of claim 1 wherein said scraper means has opposite end portions and said gantry includes support means for movably supporting said opposite end portions for raising and lowering movement of said scraper means.

10. The device of claim 9 wherein said support means comprises substantially vertical guideways on said gantry, said opposite end portions being received in said guideways.

11. The device of claim 9 wherein said support means comprises fixed bearing means for movably supporting one end of said scraper means and loose bearing means for movably supporting the other end portion of said scraper means.

12. A device for removing material from storage in a dump pile which is elongated along a predetermined path and having a substantially trapezoidal cross-sectional configuration transversely of said path and including an upper surface and opposite sloping surfaces sloping downwardly and outwardly from said upper surface, said pile having a predetermined base width, a movable gantry spanning said pile transversely of said path for movement relative to said pile along said path,

scraper means having a length substantially equal to said base width of said pile for operating on said upper surface of said pile to scrape material toward one of said sloping surfaces, suspension means for movably suspending said scraper means from said gantry for raising and lowering movement in a substantially horizontal position, clearing means independent of said scraper means for clearing material from said one sloping face of said pile, support means independent of said suspension means for supporting said clearing means from said gantry independently of said scraper means.

13. The device of claim 12 wherein said clearing means is supported on said gantry in an inclined angular position substantially corresponding to the angle of repose of material in said dump pile.

14. The device of claim 12 wherein said clearing cludes lateral support means for laterally supporting said end portions of said scraper means agalns shifting movement of said scraper means relative to said gantry in a direction parallel to the direction in which said gantry moves relative to said pile along said path.

17. The device of claim 16 wherein said gantry includes spaced-apart upright legs having substantially vertical guideways thereon defining said lateral support means. 

1. A device for removing material from a storage dump pile having a predetermined width and a sloping face, said device including a movable gantry spanning said dump pile and being movable along said pile in a direction of movement, scraper means movably supported by said gantry for raising and lowering movement in a substantially horizontal position for removing material from said pile, and clearing means supported by said gantry in a position offset from said scraper means parallel to said direction of movement of said gantry for clearing material from said sloping face of said pile.
 2. The device of claim 1 wherein said clearing means comprises two subsidiary scrapers supported by said gantry on opposite sides of said scraper.
 4. The device of claim 1 wherein said scraper means comprises a pair of scrapers positioned in parallel spaced-apart relationship and said clearing means is positioned between said pair of scrapers.
 5. The device of claim 2 and further including adjustment means for adjusting the position of said subsidiary scrapers.
 5. The device of claim 4 wherein said clearing means comprises a subsidiary scraper.
 6. The device of claim 1 wherein said scraper means has opposite end portions, suspension means movably suspending said scraper means from said gantry for raising and lowering movement in a substantially horizontal position, said suspension means being connected to said scraper means in at least two spaced-apart points intermediate said end portions.
 7. The device of claim 6 wherein said gantry haS spaced-apart upright legs, and lateral support means for laterally supporting said opposite end portions of said scraper means on said legs.
 8. The device of claim 1 wherein said clearing means comprises a subsidiary scraper having opposite end portions, and articulation means supporting at least one of said end portions on said gantry for raising and lowering movement of said subsidiary scraper.
 9. The device of claim 1 wherein said scraper means has opposite end portions and said gantry includes support means for movably supporting said opposite end portions for raising and lowering movement of said scraper means.
 10. The device of claim 9 wherein said support means comprises substantially vertical guideways on said gantry, said opposite end portions being received in said guideways.
 11. The device of claim 9 wherein said support means comprises fixed bearing means for movably supporting one end of said scraper means and loose bearing means for movably supporting the other end portion of said scraper means.
 12. A device for removing material from storage in a dump pile which is elongated along a predetermined path and having a substantially trapezoidal cross-sectional configuration transversely of said path and including an upper surface and opposite sloping surfaces sloping downwardly and outwardly from said upper surface, said pile having a predetermined base width, a movable gantry spanning said pile transversely of said path for movement relative to said pile along said path, scraper means having a length substantially equal to said base width of said pile for operating on said upper surface of said pile to scrape material toward one of said sloping surfaces, suspension means for movably suspending said scraper means from said gantry for raising and lowering movement in a substantially horizontal position, clearing means independent of said scraper means for clearing material from said one sloping face of said pile, support means independent of said suspension means for supporting said clearing means from said gantry independently of said scraper means.
 13. The device of claim 12 wherein said clearing means is supported on said gantry in an inclined angular position substantially corresponding to the angle of repose of material in said dump pile.
 14. The device of claim 12 wherein said clearing means comprises subsidiary scraper means having opposite end portions, and said support means including articulation means for supporting at least one of said end portions for raising and lowering movement relative to said gantry independently of said scraper means.
 15. The device of claim 12 wherein said scraper means has opposite end portions and said suspension means is connected with said scraper means in at least two spaced-apart points intermediate said opposite end portions.
 16. The device of claim 15 wherein said gantry includes lateral support means for laterally supporting said end portions of said scraper means against shifting movement of said scraper means relative to said gantry in a direction parallel to the direction in which said gantry moves relative to said pile along said path.
 17. The device of claim 16 wherein said gantry includes spaced-apart upright legs having substantially vertical guideways thereon defining said lateral support means. 